Premier Gladys Berejiklian has issued her strongest plea yet for people in to wear masks in public and for businesses to comply with COVID-19 regulations as NSW remains on high alert with 18 new coronavirus infections.
While the infection rate in NSW has remained stable in the past month "we can't be assured of that moving forward", she said on Wednesday.
"We need to go further. Because our concern is those cumulative accumulation of those unknown sources."
She stressed that people must wear masks when they can't guarantee social distancing on public transport, at religious services or in supermarkets.
She also warned businesses to register a COVID safe plan, especially hospitality venues, otherwise it would be assumed they had none.
"I want to see a greater uptake on all those categories and if we don't see a greater uptake in the next little while, we will consider further measures," she said.
"Compliance is absolutely critical."
NSW recorded 18 new cases of COVID19 in the 24 hours to 8pm on Tuesday, from 20,104 tests, with most from known local clusters.
NSW Chief Health Officer Kerry Chant said two new cases had been linked to Cherrybrook's Tangara School for Girls, bringing the total to 19 with the original source still unknown.
The outbreak has been associated with the nearby Catholic Opus Dei study centre for girls Eremeran, which has closed for cleaning after recently hosting five senior schoolgirls at a religious retreat.
"At the moment my guidance is that we would request all direct schools to not have activities that involve overnight stays or camps," Dr Chant said.
"We need to minimise those activities that are associated with transmission."
The premier also announced that NSW residents returning from Victoria would have their hotel quarantine fee waived for the next month to ease the financial burden on returnees.
The charge will be waived retrospectively and apply to NSW residents already in hotel quarantine after travelling from Victoria until September 11.
Dr Chant said the vast majority of the 18 new cases were from clusters within the state.
Thirteen of the cases were locally acquired and linked to known cases, one was a returned traveller from overseas, two were locally acquired without a known source, and two were acquired in Victoria.
One case was a staff member at the emergency department in Hornsby Hospital who did not work while infectious, so there had been no impact on services.
There was also a third confirmed case identified at Our Lady of Mercy College, Parramatta, which will remain closed until August 24 to allow for contact tracing. Staff and students there have been told to isolate and get tested.
Parramatta Public School was also closed on Wednesday after a student tested positive.
Dr Chant said she was most concerned about a number of cases in the past six weeks where the source was unknown, predominantly occurring in southwest and western Sydney.
"I do urge those members of the community in southwestern Sydney and western Sydney to particularly come forward for testing, should they have what is the most minimal of symptoms," she said.
Meanwhile, Huskisson restaurant Wildginger is also closed after two patrons from Sydney who dined there on Saturday evening received positive test results for COVID-19.
Patrons and staff who were at the venue have been advised to self-isolate for 14 days and get tested for COVID-19.
Anyone who attended the following venues during the dates and times below are advised by NSW Health to monitor for symptoms. If symptoms present, they should isolate and get tested:
* Rhodes Ikea on Saturday, 1.20pm -2.20pm
* Parramatta Westfield last Wednesday between 4pm-5.30pm and August 8, 12-1pm
* Dooleys Lidcombe Catholic Club from 5pm on Friday to 1.30am on Saturday
* Castle Towers Shopping Centre on Friday, 3:30-5pm
* Baby Bunting, Penrith on Saturday, 1.15pm-1.45pm
There are 133 COVID-19 cases being treated by NSW Health, with eight patients in intensive care and seven ventilated.
Australian Associated Press